Redox Reactions and oxidation-reduction

Oxidation-reduction and redox reactions, the transfer of electrons, takes place. It brings out the chemical reactants which are involved in the reaction. Every redox reaction is divided into the reduction process and oxidation process. In these reactions, the oxidation states of the chemical reactants are changed. The short form of reduction-oxidation is known as redox. Redox or Oxidation-Reduction reactions, an oxidation and reduction potential reaction occurring simultaneously. The part that gets reduced during a chemical reaction is called the oxidising agent, whereas the part that gets oxidised during a chemical reaction is called the reducing agent. 

What is meant by Redox Reactions?

Redox reaction is a chemical reaction in which the transfer of electrons occurs. It takes place between the reactants involved in the reaction. Differences in the oxidation states of the reactants point to the transfer of electrons. Let us discuss this in brief. It has been observed that an electron is removed from one reactant, and the reactant gets oxidised. Whereas the electron is transferred to another reactant, and it gets reduced. 

An increase in the oxidation state of a chemical reactant and loss of electrons is known as oxidation. The decrease in the oxidation state and gain of electrons is known as reduction.

We have two species in the redox reactions, the electron-accepting and electron-donating species. An electron species that go for a reduction in redox reactions are known as oxidising agents. Electron-donating species are the ones that give over electrons and are known as reducing agents. 

The redox reaction is divided into two half-reactions, i.e. the oxidation half-reaction and the reduction half-reaction. 

Kinds of Redox Reactions 

There are four types of redox reactions. These are:-

• Decomposition Reaction

• Combination Reaction

• Displacement Reaction

• Disproportionation Reactions

Decomposition Reaction

In this reaction, components are broken down into various components. 

 Examples:-

• 2NaH → 2Na + H₂

• 2H₂O → 2H₂ + O₂

• Na₂CO₃ → Na₂O + CO₂

In the above reaction, all components are broken down into different components.

Special Case:- Although, there is one special case that ensures that every decomposition reaction is not a redox reaction. 

Example:-CaCO₃ → CaO + CO₂

Combination Reaction

A combination reaction is the opposite of a decomposition reaction. Two compounds are combined to form a single compound.  

Example:-

• H₂ + Cl₂ → 2HClC+O₂→CO₂

• 4 Fe+ 3O₂→2Fe₂O₃

Displacement Reaction

An atom on an ion is replaced by another atom or ion element.

It is of two types:-

• Metal displacement Reaction

• Non-metal displacement Reaction

• Metal Displacement

Such reactions are very useful in the metallurgical processes. The metal in one compound is used to be replaced by another metal. This reaction does the extracts of pure metals from their ores.

Example:-CuSO₄+Zn→Cu+ZnSO₄

• Non-Metal Displacement

In a Non-displacement reaction, hydrogen displacement takes place. Infrequently the oxygen displacement also takes place.

Disproportionation Reactions

In Disproportionation reactions, a single reactant is oxidised as well as reduced. 

Example:- P₄ + 3NaOH + 3H₂O → 3NaH₂PO₂ + PH₃

Let us discuss an example of a redox reaction. 

The reaction between iron and hydrogen peroxide:-

In this reaction, Fe2+ is subjected and oxidised to Fe3+. 

The complete reaction is written below:-

2Fe2+ + H2O2 + 2H+ → 2Fe3+ + 2H2O

In first half, oxidation reaction takes place: Fe2+ → Fe3+ + e–

In the next half, a reduction reaction takes place: H2O2 + 2e– → 2 OH–

In reducing hydrogen peroxide, hydroxide ions are formed, which combines with the proton contributed by the acidic medium to form H2O.

About Oxidation and Reduction Reaction

Let us discuss oxidation and reduction reactions separately to understand redox reactions well 

• What is meant by Oxidation Reaction?

The loss of electrons from a chemical reactant is called oxidation.

An oxidation definition involves adding oxygen or the additional electronegative element or removing hydrogen or the additional electropositive element from a chemical reactant.

Go through the example to have more clear view:-

2S(s) + O₂ (g) → SO₂ (g) CH₄ (g) + 2O₂ (g) → CO₂ (g) + 2H₂O (l)

• What is meant by Reduction Reaction?

It is the opposite of an oxidation definition. Because in reduction potential, the gain of electrons occurs. In a chemical reaction, a chemical reactant gains electrons and gets reduced.

The reduction reaction involves adding hydrogen or additional electropositive elements or removing a more electronegative element or oxygen from a chemical substance.

Go through the examples to have a clearer view:-

• 2CH₂CH₂ (g) + H₂ (g) → CH₃CH₃ (g)

• 2FeCl₃ (aq) + H₂ (g) → 2FeCl₂ (aq) + 2HCl (aq)

In the above reaction, oxidation and reduction occur simultaneously.

Conclusion:

In redox reactions, oxidation and reduction occur one after the other. The redox reaction is not only done on chemical reactants but also has real-life uses. The element is oxidised when its oxidation number is increased and reduced when it decreases. Redox or oxidation-reduction involves the transfer of electrons. In an oxidation reaction, the chemical reactant combines with oxygen. Redox reactions are used in the electroplating process, which is done on gold-plated jewellery. The oxidation and reduction reaction in chemistry is a redox or oxidation-reduction reaction.